On 2021-11-02 16:10:44, Jan Stary <[email protected]> wrote:
> This is current/amd64 on a PC, using lpr with this /etc/printcap:
> lp::lp=:rm=pr.stare.cz:rp=lp:sd=/var/spool/output/lpd:lf=/var/log/lpd-errs:sh:
> which is a Brother DCP9055CDN via ethernet.
>
> Now, I have this pdf file (attached), broken in a way that puzzles me.
> When viewed with mupdf or gv, it shows one thing, when printed with lpr,
> it shows something else.
>
> [snip]
>
> Is that an indication of some particular kind
> of breakage in a pdf file?
>
> [snip]
>
I have no idea if this is the same issue affecting you, but it
reminded me of how JBIG2 compression can alter text.
To quote Wikipedia [1],
"When used in lossy mode, JBIG2 compression can
potentially alter text in a way that's not discernible as
corruption. ... Since JBIG2 tries to match up similar-looking
symbols, the numbers "6" and "8" may get replaced, for example."
This issue first came to light when it was found that scanned
documents had different numbers in the digital representation than
were on the original. In one case, an engineer reported that the
size of a room on a technical blueprint changed from 21.11 m^2
down to 14.13 m^2 due to the way that the compression was being
erroneously applied.
However, this was reported when *scanning* documents. Your issue
is with *printing* documents. I have no idea if this is the same
issue as what you're experiencing, but I thought it still might be
worth pointing out in case there's some connection between the
two.
[1] https://en.wikipedia.org/wiki/JBIG2#Disadvantages
--
Bryan
